Ethanol Extract from Aerial Parts of Waltheria indica (Sleepy Morning) Ameliorates Scopolamine-Induced Amnesia in Wistar Albino Rats

Waltheria indica, commonly known as Sleepy Morning, is renowned for its neuroprotective bioactive constituents and long-standing use in managing neurological disorders. This study investigated the neuroprotective efficacy of its ethanol extract against scopolamine-induced amnesia in Wistar albino rats, a model that mimics Alzheimer-like cognitive decline. Thirty-six adult male Wistar rats were divided into six groups (n=6). Group 1 (control) received normal saline (10 ml/kg, orally), while Group 2 received piracetam (200 mg/kg, standard drug) plus scopolamine. Groups 3, 4, and 5 were administered 200, 400, and 800 mg/kg of W. indica extract, respectively, followed by scopolamine. Group 6 (amnesic control) was given scopolamine (1.0 mg/kg) and saline. After seven days of treatment, learning and memory were evaluated using the Morris water maze and passive avoidance tests. Rats were then fasted for twelve hours, and brain tissues were analyzed for acetylcholinesterase (AChE) activity and oxidative stress biomarkers—superoxide dismutase (SOD), catalase (CAT), and malondialdehyde (MDA). Pretreatment with W. indica extract significantly (P < 0.05) enhanced memory performance compared with the scopolamine group. Biochemically, the extract increased CAT and SOD activities and reduced MDA levels and AChE activity, suggesting decreased oxidative stress. These findings indicate that ethanol extract of Waltheria indica mitigates scopolamine-induced cognitive dysfunction through antioxidant mechanisms and cholinesterase inhibition.